1. Field of the Invention
The present invention relates to a bridge-type ultrasonic atomizer by means of using at least one piezoelectric substrate and a porous nonmetalic-plate.
2. Description of the Prior Art
Conventional ultrasonic atomizer such as a nebulizer-type atomizer has difficulties in miniaturizing device size, and making electric power consumption down. The ultrasonic vibrating device presented by Toda in U.S. Pat. No. 5,297,734, realized high atomization efficiency and high ability for atomizing minute and uniform particles. In addition, Toda (U.S. Pat. No. 5,297,734) made device size miniaturize. However, Toda (U.S. Pat. No. 5,297,734) failed in making operation voltage down, and making circuit construction simple, and had no way to conquer the resonance frequency deviation affected by the temperature change, that is, failed in continuous-stable atomization. A way to conquer the resonance frequency deviation affected by the temperature change is disclosed in the ultrasonic atomizing device presented by Toda in U.S. Pat. No. 5,657,926. Toda (U.S. Pat. No. 5,657,926) realized continuous-stable atomization under low voltage with low electric power consumption. However, Toda (U.S. Pat. No. 5,657,926) failed in producing standardized articles in the process of manufacturing, because a cementing condition of a vibrating plate 2 to a piezoelectric vibrator 1 (Toda, U.S. Pat. No. 5,657,926, FIG. 1) makes a change in length of the assembly composed of the piezoelectric vibrator 1 and the vibrating plate 2. The change in length of the assembly causes a change in operation frequency. A lack of unity of the operation frequency is undesirable for circuit construction.
This application is an improvement on the Toda application (U.S. Pat. No. 5,657,926).
An object of the present invention is to provide a bridge-type ultrasonic atomizer capable of atomizing under low voltage with low electric power consumption.
Another object of the present invention is to provide a bridge-type ultrasonic atomizer capable of atomizing minute and uniform particles.
Another object of the present invention is to provide a bridge-type ultrasonic atomizer capable of conquering the resonance frequency deviation affected by the temperature change.
Another object of the present invention is to provide a bridge-type ultrasonic atomizer capable of continuous-stable atomization.
Another object of the present invention is to provide a bridge-type ultrasonic atomizer having a small size and a simple structure, which is very light in weight.
A still other object of the present invention is to provide a bridge-type ultrasonic atomizer capable of producing standardized articles in the process of manufacturing.
A still further object of the present invention is to provide a bridge-type ultrasonic atomizer capable of preventing the operation without liquid.
According to one aspect of the present invention there is provided a bridge-type ultrasonic atomizer comprising an input piezoelectric substrate with a pillar body having two end surfaces orthogonal to the thickness direction thereof, first- and second electrodes formed on one and the other end surfaces, respectively, of the input piezoelectric substrate, third- and fourth electrodes formed on one and the other end surfaces, respectively, of the output piezoelectric substrate, a porous nonmetalic-plate formed as a bridge between the input- and output piezoelectric substrates, and an amplifier.
When an input electric signal is applied between the first- and second electrodes, a first acoustic vibration is excited in the input piezoelectric substrate. The first acoustic vibration propagates in the porous nonmetalic-plate. In this time, if a liquid exists in pierced pores of the porous nonmetalic-plate, the liquid is atomized toward the outside. The first acoustic vibration also causes a second acoustic vibration in the output piezoelectric substrate only when the liquid exists in the pierced pores. The second acoustic vibration is detected as a delayed electric signal between the third- and fourth electrodes. The delayed electric signal is amplified via the amplifier, and an amplified electric signal is fed as the input electric signal back to the first- and second electrodes again.
According to another aspect of the present invention there is provided a bridge-type ultrasonic atomizer, wherein the input electric signal has a frequency approximately equal to the resonance frequency in the combination of the input- and output piezoelectric substrates.
According to another aspect of the present invention there is provided a bridge-type ultrasonic atomizer, wherein the input electric signal has a frequency approximately equal to the resonance frequency in the input piezoelectric substrate alone.
According to another aspect of the present invention there is provided a porous nonmetalic-plate having a specific gravity smaller than the input- and output piezoelectric substrates, respectively.
According to another aspect of the present invention there is provided a porous nonmetalic-plate made of a rigid polymer plate.
According to another aspect of the present invention there is provided a porous nonmetalic-plate made of a silicone wafer.
According to another aspect of the present invention there is provided an input piezoelectric substrate having two end surfaces, of which each has an oblong shape. In this arrangement, the porous nonmetalic-plate is cemented with an edge on the second electrode and that on the fourth electrode.
According to another aspect of the present invention there is provided an input piezoelectric substrate having two end surfaces, of which each has a square shape. In this arrangement, the porous nonmetalic-plate is cemented with an edge on the second electrode and that on the fourth electrode.
According to another aspect of the present invention there are provided input- and output piezoelectric substrates, of which each is made of a piezoelectric ceramic and has a polarization axis parallel to the thickness direction thereof.
According to another aspect of the present invention there is provided a liquid provider with a liquid-absorption material, which provides the porous nonmetalic-plate with a liquid.
According to another aspect of the present invention there is provided a bridge-type ultrasonic atomizer comprising a piezoelectric substrate with a pillar body having two end surfaces orthogonal to the thickness direction thereof; first- and second electrodes formed on one and the other end surfaces, respectively, of the piezoelectric substrate, a vibration reflector, and a porous nonmetalic-plate formed as a bridge between the piezoelectric substrate and the vibration reflector.
When an input electric signal having a frequency approximately equal to the resonance frequency in the piezoelectric substrate alone is applied between the first- and second electrodes, an acoustic vibration is excited in the piezoelectric substrate. The acoustic vibration propagates in the porous nonmetalic-plate. In this time, if a liquid exists in pierced pores of the porous nonmetalic-plate, the liquid is atomized toward the outside. On the other hand, the acoustic vibration is reflected at the vibration reflector back to the porous nonmetalic-plate.
According to other aspect of the present invention there is provided a piezoelectric substrate made of a piezoelectric polymer.
According to a further aspect of the present invention there is provided a bridge-type ultrasonic atomizer comprising a piezoelectric substrate with a pillar body having two end surfaces orthogonal to the thickness direction thereof, first- and second electrodes formed on one and the other end surfaces, respectively, of the piezoelectric substrate, a vibration reflector, and a porous nonmetalic-plate formed as a bridge between the piezoelectric substrate and the vibration reflector. The second electrode consists of two electrically separated electrodes.
When an input electric signal having a frequency approximately equal to the resonance frequency in the piezoelectric substrate alone is applied between the first electrode and one of the electrically separated electrodes, an acoustic vibration is excited in the piezoelectric substrate. The acoustic vibration propagates in the porous nonmetalic-plate. In this time, if a liquid exists in pierced pores of the porous nonmetalic-plate, the liquid is atomized toward the outside. On the other hand, the acoustic vibration is reflected at the vibration reflector back to the porous nonmetalic-plate. The acoustic vibration in the piezoelectric substrate also causes a delayed electric signal between the first electrode and the other of the electrically separated electrodes. The delayed electric signal is fed as the input electric signal back to the first electrode and the one of the electrically separated electrodes again.